20685232720 has 20 divisors (see below), whose sum is σ = 48093166260. Its totient is φ = 8274093056.

The previous prime is 20685232703. The next prime is 20685232727. The reversal of 20685232720 is 2723258602.

It can be written as a sum of positive squares in 2 ways, for example, as 3169239616 + 17515993104 = 56296^2 + 132348^2 .

It is a tau number, because it is divible by the number of its divisors (20).

It is a self number, because there is not a number n which added to its sum of digits gives 20685232720.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20685232727) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 129282625 + ... + 129282784.

It is an arithmetic number, because the mean of its divisors is an integer number (2404658313).

Almost surely, 2^20685232720 is an apocalyptic number.

20685232720 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20685232720 is an abundant number, since it is smaller than the sum of its proper divisors (27407933540).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

20685232720 is a wasteful number, since it uses less digits than its factorization.

20685232720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 258565422 (or 258565416 counting only the distinct ones).

The product of its (nonzero) digits is 80640, while the sum is 37.

The spelling of 20685232720 in words is "twenty billion, six hundred eighty-five million, two hundred thirty-two thousand, seven hundred twenty".